The invention relates to a weight compensation device for a drive of a lifting door for the position-dependent compensation of the weight force of a door leaf of the lifting door, with a force transmission unit which can be coupled to the drive in order to carry out an opening movement which raises the door leaf and a closing movement which lowers the door leaf.
A generic weight compensation device is known from GB 570,469.
From prior art, lifting doors with integrated weight compensation devices are moreover known. For example, DE 40 15 214 A1 discloses a lifting door with a slatted armor with bending slats. The lifting door disclosed therein comprises two guide tracks disposed at the two opposite sides of the door aperture, and a slatted armor with slats placed on hinge straps at such a distance to each other that the hinge pins engage within a space between the adjoining slats. It is furthermore disclosed that this lifting door is configured as an industrial lifting door in the sense of a high-speed lifting door. Such lifting doors are configured as rolling doors which close or open walk-through or drive-through door apertures.
It is known from DE 40 15 214 A1 that tension springs are employed for compensating the weight of the individual slats forming the door leaf. However, a disadvantage of tension springs consists in that they only have a service life of about 200,000 lifts.
Torsion springs employed as an alternative have an even shorter service life of about 30,000 to 40,000 lifts.
The often employed tension springs even have yet another disadvantage, i.e. they require a lot of installation space for heavy doors which must be available in particular at the sides of the door aperture. If a frame of the door is not wide enough to receive adjoining tension springs which provide the required supporting spring force, it is also possible to dispose them one behind the other, but both types affect efficient space utilization in the region of a lifting door.
From prior art, alternative weight compensation devices, which are employed, for example, in sectional doors, are also known. For example, DE 102 32 577 A1 discloses a weight compensation device for a sectional door with a rotatably mounted shaft, a rope drum at least at one end of the shaft on which a traction rope connected to the door leaf of the sectional door is connected, and at least one torsion spring configured as a coil spring. The coil spring is retained at one spring end at a stationary receiving part and at the other spring end at a receiving body fixed to the shaft and acts as torsion spring having a particularly short service life.
Even the employment of hydraulic accumulators in industrial lifting doors does not represent an optimal embodiment because constructions employing such hydraulic accumulators are expensive and complex.
It is therefore the object of the present invention to avoid the disadvantages of prior art and to provide an inexpensive, long-life weight compensation device which may be employed in doors where foil-like door leaves or several hinged, preferably rigid segments are lifted, such as spiral doors or doors that employ the drum principle.
This object is achieved according to the invention by a weight compensation device having the features disclosed herein. Such compression springs may bear higher loads over years as compared to tension and especially torsion springs, without any failure occurring already after a relatively short time of use or maintenance works having to be performed at an early stage. In tests performed at certain compression springs, no essential spring deformations showed after one million lifts. The compression spring is arranged in a hollow-cylindrical guide element, the hollow-cylindrical guide element being attached to a mount so as to rotate or, alternatively, in a torque-proof manner, for supporting a rotary motion of the force transmission unit. This permits efficient spring force utilization with a compact design.
A solution according to the invention is therefore not only inexpensive and long living, but also permits the advantage of a particularly simple and efficient construction.
Advantageous embodiments are claimed in the subclaims and will be illustrated more in detail below.
For example, it is advantageous for the compression spring to be coupled to a motion conversion device which employs the force acting in the longitudinal direction to the compression spring for supporting a rotary motion of the force transmission unit that raises or lowers the door leaf. The motion conversion device therefore utilizes the force that can be stored in a compression spring to transfer a supporting torque to the force transmission unit.
It is furthermore advantageous for the compression spring to be arranged essentially horizontally, preferably transversely to the lifting or lowering direction of the door leaf. Thereby, the installation space may be well utilized.
The weight compensation device may be particularly compactly realized when the door leaf surrounds a hollow space in its lifted, wound-up state where the compression spring and/or the motion conversion device are arranged.
To be able to realize spiral doors and drum doors in a particularly easy way, it is advantageous for the guide element to embody a torque-proof hollow cylinder, or for the guide element to embody the drive shaft configured as hollow shaft.
The force of the compression spring may be particularly efficiently used as supporting torque for compensating the weight of the door leaf if the compression spring supports itself at a base part fixed with respect to the guide element and an adjusting element translationally movable relative to the guide element with force transmission.
An advantageous embodiment is characterized in that the drive shaft is in active relation with the adjusting element which is movable in a longitudinal direction of the drive shaft by the compression spring.
A transmission-like embodiment may be achieved if the adjusting element is coupled to the drive shaft so as to transmit torques, preferably in such a way that a movement of the adjusting element along the longitudinal direction enforces torque transmission from the adjusting element to the drive shaft.
In order to avoid any rotation of the adjusting element, for example when the drive shaft is rotating, it is advantageous for the adjusting element to be guided within the hollow shaft so as to be movable in the longitudinal direction, preferably in a groove on the inner side of the hollow shaft which preferably extends essentially in the longitudinal direction. However, it is also possible for the groove to be present at the adjusting element and corresponding diametrically opposed projections to be present on the inner side of the hollow shaft.
If the adjusting element is configured as a spindle nut, one may use a tried and tested conversion element. By this, high forces may be transmitted and components be used that are loadable over a long time.
It is particularly suitable for the spindle nut to be coupled to the drive shaft by threaded engagement. The spring force of the compression spring may be then particularly easily supportively impressed on the drive shaft.
A further advantageous embodiment is characterized in that at least one flexible clutch is embodied in the drive shaft which splits up the latter. Such a flexible clutch, in particular of a claw clutch type, is advantageous for compensating a mechanical overdetermination between lateral bearings which are employed for mounting the drive shaft. It is possible to only use plain bearings on the one side of the claw clutch, whereas on the other side of the claw clutch, a thrust bearing and a plain bearing are combined. It is also possible to use several flexible clutches, such as claw clutches, axially one behind the other and to arrange the corresponding bearings outside these flexible clutches.
The invention also relates to a lifting door, in particular an industrial lifting door, which comprises a door leaf, with a drive, such as a motor, and an inventive weight compensation device as illustrated above. Such a motor may be, for example, an electric motor or a hydraulic or pneumatic motor. Even internal combustion engines are possible power units.
It is then furthermore advantageous for a control window to be provided in the hollow shaft which permits a view to the spindle nut. In this manner, the adjustment of the individual elements with respect to each other becomes controllable.
It is advantageous for the control window to extend along the longitudinal direction and to be preferably oriented horizontally, so that a readjustment or an initial adjustment of the individual elements may be particularly easily controlled. Such a horizontal orientation offers itself especially due to the fact that the hollow shaft, i.e. the drive shaft, is normally arranged such that it extends above the door aperture in the horizontal direction.
If the spindle nut comprises an end plate for which an assembly position is marked in the control window, even untrained personnel may easily perform adjustment and assembly.
It is furthermore advantageous if during the assembly of the lifting door, the coupling between the motor and the spindle nut may be cancelled to bring the spindle nut into a desired assembly position preferably manually and/or using a crank, where coupling may be restored in this position. In this context, a method which uses the control window to bring the end plate, after a decoupling of the corresponding elements, back into the planned position and then restore the coupling is also advantageous.